The present invention relates to a data writing apparatus for optically writing the number of film frames, brand, emulsion lot number, bar code, characters, and symbols (hereinafter referred to as the data) onto the non-exposed film thereon in the course of the production process of the roll film to be used for cameras, and further relates to an apparatus wherein an improvement has been implemented with respect to the data-reading process which is so designed as to read out the data from a memory storing the writing data.
This type of apparatus is so designed as to perform the data writing function as feeding the film at a given velocity after slitting the non-exposed film into strips having a given width, wherein the non-exposed film have been applied thereon with the photosensitive materials and have been processed to form perforations as feeding holes.
As for the conventional data writing apparatus as described above, there has been known an apparatus wherein there is provided an exposure means for writing symbols having different colors along the film proceeding path. Another example of this type is an apparatus disclosed in the Japanese Patent Publication No. 19564/1985 wherein there are provided dot light projectors consisting of plural guiding members for guiding respective different color light of each LED or the like for optically writing the dots. In the dot light projectors, light-outgoing ends of the optical members are bundled so as to cause the color distribution therefrom to be uniform. A plurality of the dot light projectors are so arranged in a line that the light therefrom can be collected by means of a lens and then be irradiated onto the film.
The former has a disadvantage that only those colors and symbols present in the range limited by the number of the exposure means can be written. The latter, on the other hand, has the following disadvantages: First, the LEDs to be used are required in number equivalent to the value obtained by means of multiplying the number of LED types by the number of the dot light projectors, thus numerous number of LEDs are necessary. Second, when such numerous number of LEDs are used, the area of the dot light projectors becomes great in scale, because the dot light projectors are formed by means of bundling the light-outgoing end of the optical guide members, thus it becomes difficult to write such data including fine dots and lines. Third, even though apparently the written dots may seem to have a uniform color pattern for human eyes, those dots are actually composed of distribution of different color stops. Moreover, in the case of writing seven colors by means of turning on all three LEDs, for example, blue (B), green (G), and red (R), or by means of turning on two lights out of them, or by means of turning on only one light out of them, the distribution density of the color spots of the dots becomes uneven, except in the case all three lights are turned on, thus resulting in the possibility to cause the false information when reading the data which can be interpreted in various ways.
In addition, as for the data writing apparatus using the dot system other than those described above, there has been known an apparatus, as disclosed in the Japanese Patent Publication No. 119422/1984, wherein a multiplicity of light projectors to be used for performing small circular exposures with respect to the film, are so arranged as to be positioned in a line in the direction being right angle to the film proceeding direction so that each small circular exposure areas are juxtaposed, and by means of relating those light projectors with the movement of the film so as to allow the light projectors to selectively light, thus the data such as characters and figures composed of dots can be written in the film; however, according to this apparatus, the color of the data cannot be changed.
Furthermore, since the data having the dot construction to be written by the conventional data writing apparatus as mentioned above, are composed of the small circular dots in matrix arrangements consisting of the proceeding direction of the film as well as the direction being right angle to the film proceeding direction, or in a matrix arrangement some of whose dots are removed from the above matrix arrangement, consequently, a vacant space is generated between the dot arrangements. Thus, in the case of optically reading the data of the bar code which shows the printing conditions of the film, there has been a problem that no accurate information has been obtained, because the density level of the bar portion of the bar code varies to a great extent due to the vacant portion or the non-exposed portion present between the dots.
Further, when writing the data using the conventional data writing apparatus as described above, the data to be written had been stored beforehand in the memory with the dot information as well as the film position information, and the position signals occurring in synchronization with the film feeding action are detected, and then the information read out from the memory using the CPU with a complex processing program are written.
In other words, in the conventional data writing apparatus, the CPU and such complex processing program are indispensable factors, thus requiring quite a long time from detecting the film position to the writing operation, which acted as an impeding factor for increasing the film feeding velocity as well as enhancing the dot density. Also, there was an additional problem that if there was an irregularity in the film feeding velocity, the data writing position could not come at the correct position.